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Forum: Photographic Technique
02-26-2018, 08:01 PM
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I've used it a bit now on tripod.
Very useful for photographing art, products, copy work, and the like.
Street photography not so much.
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Forum: Photographic Technique
09-24-2017, 03:37 PM
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Yes, the ps image will look at every pixel site for colour - but that is still not the same thing as resolution.
The solid red thing is a red herring for two reasons - the first is that the demosaisizer algorithm will return a 36mp red image if all it can see is red - it won't return 9mp (an image with 99.9% red and random scattered green & blue flecks would likely fail - but honestly who does that?)
Secondly, the demosaisizer algorithm looks at surrounding pixels to determine colour, but you are forgetting that it also looks at each pixel individually to work out the gamma - a false colour simply cannot be lighter than the representative pixel.
The sub sampling effectively happens twice - once for colour and once for light & dark - The edges in a normal image are typically represented by tonality more than colour.
This is kinda fun - I could imagine us having an interesting conversation over coffee.
Have you considered the implications of polarisation on this - given that the waveform amplitude of different coloured light are different and the probability of those light streams impacting different pixel sites differently at the edges given the time difference between frames. I might have to have a play to see if it's a thing :)
I think we are agreeing though that hand held pixel shift is a bad idea and likely to degrade the image.
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Forum: Photographic Technique
09-23-2017, 07:08 PM
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That was actually what I said.
The way that I am using the term 'resolution' is in referencing line pairs per mm in the image.
By that logic;
resolution is how many pixels across the image is by how high, you need more pixels to have more resolution - You need at least three horizontal pixels to represent a vertical line pair, hence the whole megapixel race thing.
Colour depth is how much information there is at each pixel site. hence the idea of foveon sensors or Pixel Shift, which does make it easier to percieve subtle edges.
There is four times the information in the raw file because each pixel site is sampled four times - the resolution isn't quadrupled, the colour depth per pixel is.
(bar the edges I guess, because trigonometry & physics & stuff)
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Forum: Photographic Technique
09-23-2017, 04:58 PM
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I've only skim read to here, so I apologize if I've missed something, but something that leaped out at me is the motion correction bit.
My understanding from usage (along with doing product photography as well as rebuilding sensors for IR etc) runs like;
You only really want to ever use pixel shift on a tripod, not hand held.
Motion correction is to compensate for movement in the scene, not movement of the camera - so it's useful in a landscape where you have the camera on a tripod, but there might be occasional light puffs of wind and you might have some leaves moving in one shot and not in the others (one from four), so the camera will subtract that part of that frame where the movement occurred (leaving three from four frames to average the colour of the pixel).
If you use this feature handheld you are likely to have movement between all frames, so you will have only one of four frames taken, or you will have glitches in the image where the camera has misjudged what colour a section is - either way no advantage over a single frame hand held.
If you are in a studio where nothing will move between frames you want to turn the movement correction off - this is when everything it totally locked down (this is the ideal scenario).
Pixel shift will not increase resolution, it will increase colour depth per pixel, and thus it will increase the level of information in the image - A regular bayer sensor will create an image with a colour structure like;
R G R G R G R G R
G B G B G B G B G
So for each cluster of four pixels on the sensor you will have RGBG represented, which is then converted to RGB for the final image
A Foveon sensors image or a pixel shifted image will have a read like
RGB RGB RGB RGB RGB RGB
RGB RGB RGB RGB RGB RGB
Thus it will have far more colour information per pixel site in the resultant image.
While this does result in a perception of increased detail, this is due to more accurate colour information rather than a greater number of pixels (which is how you get more detail).
You still get the same level of stepping at a pixel level, just the averaging (and thus perception of detail) is better at an image level due to the greater amount of colour information per pixel in the image.
If you want to do this handheld you are better off shooting four frames and using photoshop to allign and merge them manually and then erase sections where local movement occurred.
Otherwise you might also take one frame, duplicate the layer, change the size of one of the layers by one pixel and then use layer effects to increase the colour depth per pixel for printing (I used to use a technique like that years ago for printing large prints with small files - I haven't felt the need to do it since the 10MP days so my memory of the methodology is a bit hazy).
Hopefully someone will make sense of what I just said and be able to translate it from me to not-me. :)
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